Substituted Aliphatic Acids. 



489 







Table II.- 



—Summary. 







Temperature 



25° 



35° 



45° 



25°-35° 

 Temp. 



35-45 



Temp. 





10 5 K 



10 5 K 



10 5 K 



Coeff. 



Coeff. 



Ethyl 













propionate 



71*6 



179' 



406 



2-50 



2-26 



Ethyl 













lactate 



73-2 



178- 



396- 



2'43 



2*22 



Ethyl 













glycerate 



18-5 



43-9 



101' 



2-43 



2-20 



Ethyl 













a-ethyloxy 













propionate 



19-7 



49-5 



111' 



2-51 



2-24 



Ethyl 













/?-ethyloxy 













propionate 



14-3 



35-2 



84-7 



2-45 



2-41 



Ethyl 













acetate 



64-7 



163- 



374- 



2-51 



2*29 



Ethyl 













glycollate 



70-4 



173 



392- 



2-45 



2-26 



Discussion of Results. 



The general results brought out by these figures need no 

 extended discussion. There are, however, several points which 

 are evident only on a close examination of the tables. In the 

 first place it will be noticed that the temperature coefficient 

 of the hydroxy esters is low. This is shown in the cases of 

 glycerate, lactate and glycollate. The figures for the last 

 ester are repeated from tables in a previous paper. In the 

 case of lactate and propionate this difference in the tempera- 

 ture coefficient is sufficient to cause the former to hydrolyze 

 more slowly than the latter at 45°, while at 25° its constants 

 are greater. These differences are small, but are nevertheless 

 very clearly marked. The second fact to which attention is 

 called is that ethyl glycerate hydrolyzes very slowly. This 

 means that the presence of hydroxyl groups in alpha and beta 

 positions causes an entirely different effect from that produced 

 by the substitution of a single radical. 



From these two facts it would seem that the effect on ester 

 hydrolysis in acid solution cannot be considered as an additive 

 property for all substituted groups. It is here shown that the 

 same group may cause either a slight acceleration or retardation 

 accordingly as the temperature is high or low. It also appears 

 that the presence of two hydroxyl groups may produce a strong 

 decrease of velocity whereas one tends on the whole toward an 

 acceleration. 



A single other point is worthy of special mention. An 

 ethyloxy group in the alpha position produces a retardation of 



